Power tool

ABSTRACT

A rotary hammer operable in a first mode in which only a hammering operation to reciprocate a tool bit along a drive axis is performed and a second mode in which the tool bit is rotationally driven about the drive axis. The rotary hammer includes a motor, a controller to control operation of the motor, a trigger moveable between an off position and an on position, a mode selection dial operable to select the first or second mode, a lock mechanism moveable between a first position and a second position, a linkage moveable between a third position and a fourth position, and a switch in communication with the controller. The switch communicates with the controller to operate the motor at full power or communicates with the controller to operate the motor at a variable speed based on the position of the trigger between the on position and the off position.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of co-pending U.S. Provisional Patent Application No. 63/328,852, filed on Apr. 8, 2022, the entire content of which is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to power tools, and more particularly to rotary hammers.

BACKGROUND OF THE INVENTION

Power tools such as, for instance, rotary hammers, are generally operable in at least two modes, rotary hammer mode and hammer only mode. In rotary hammer mode, the rotary hammer imparts rotation and axials impacts to a drill bit while performing a drilling or breaking operation on a work surface. In hammer only mode, the rotary hammer only imparts axial impacts to the drill bit. While in hammer only mode, a user may desire a lock-on of a trigger to continuously activate a motor to impart axial impacts without the need to manually depress the trigger.

SUMMARY OF THE INVENTION

The invention provides, in another aspect, a rotary hammer operable in a first mode in which only a hammering operation to reciprocate a tool bit along a drive axis is performed and a second mode in which the tool bit is rotationally driven about the drive axis. The rotary hammer includes a motor, a controller to control operation of the motor, a trigger moveable between an off position, in which the motor is not energized, and an on position, in which the motor is energized, a mode selection dial operable to select the first or second mode, a lock mechanism moveable between a first position, in which, the trigger is moveable between the on and off positions, and a second position, in which the trigger is maintained in the on position, a linkage moveable between a third position, in which, when the mode selection dial selects the first mode, the lock mechanism is able to move between the first and second positions, and a fourth position, in which, when the mode selection dial selects the second mode, the lock mechanism is inhibited from moving between the first and second positions, and a switch in communication with the controller. The switch, in a first state, communicates with the controller to operate the motor at full power, and the switch, in a second state, communicates with the controller to operate the motor at a variable speed based on the position of the trigger between the on position and the off position.

The invention provides, in one aspect, a rotary hammer operable in a first mode in which only a hammering operation to reciprocate a tool bit along a drive axis is performed and a second mode in which the tool bit is rotationally driven about the drive axis. The rotary hammer including a motor, a controller to control operation of the motor, a trigger moveable between an off position, in which the motor is not energized, and an on position, in which the motor is energized, a mode selection dial operable to select the first or second mode, a lock mechanism including a shuttle moveable linearly between a first position, in which, the trigger is moveable between the on and off positions, and a second position, in which the trigger is maintained in the on position, a linkage moveable between a third position, in which, when the mode selection dial selects the first mode, the shuttle is able to move from the first position to the second position, and a fourth position, in which, when the mode selection dial selects the second mode, the shuttle is inhibited from moving from the first position to the second position, and a switch in communication with the controller. The switch, in a first state, communicates with the controller to operate the motor at full power, and the switch, in a second state, communicates with the controller to operate the motor at a variable speed based on the position of the trigger between the on position and the off position.

The invention provides, in one aspect, a rotary hammer operable in a first mode in which only a hammering operation to reciprocate a tool bit along a drive axis is performed and a second mode in which the tool bit is rotationally driven about the drive axis, the rotary hammer including a motor, a trigger moveable between an off position, in which the motor is not energized, and an on position, in which the motor is energized, a mode selection dial operable to select the first or second mode, a lock mechanism including a shuttle moveable in a direction parallel to the drive axis between a first position, in which the trigger is moveable between the on and off positions, and a second position, in which the trigger is maintained in the on position, and a linkage moveable between a third position, in which, when the mode selection dial selects the first mode, the shuttle is able to move from the first position to the second position, and a fourth position, in which, when the mode selection dial selects the second mode, the shuttle is inhibited from moving from the first position to the second position.

Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a rotary hammer.

FIG. 2 is a top view of the rotary hammer of FIG. 1 illustrating a mode selector dial.

FIG. 3 is a top view of the rotary hammer of FIG. 1 illustrating a chisel lock-on mechanism.

FIG. 4 is a side view of a portion of the chisel lock-on mechanism of FIG. 3 in a unlocked position.

FIG. 5 is a side view of a portion of the chisel lock-on mechanism of FIG. 3 in a locked position.

FIG. 6 is a side view of the rotary hammer of FIG. 1 illustrating a chisel lock-on mechanism according to another embodiment of the invention.

FIG. 7 is a side view of the rotary hammer of FIG. 1 illustrating a chisel lock-on mechanism according to another embodiment of the invention.

FIG. 8 is a side view of the rotary hammer of FIG. 1 illustrating a chisel lock-on mechanism according to another embodiment of the invention.

FIG. 9A is a side view of the rotary hammer of FIG. 1 illustrating a chisel lock-on mechanism in an unlocked position according to another embodiment of the invention.

FIG. 9B is a side view of the chisel lock-on mechanism of FIG. 9 in a locked-on position.

FIG. 10A is a top view of the rotary hammer of FIG. 9 illustrating a mode selector dial in a first position.

FIG. 10B is a top view of the rotary hammer of FIG. 9 illustrating a chisel lock-on mechanism in a first position.

FIG. 11A is a top view of the rotary hammer of FIG. 1 illustrating a mode selector dial in a second position.

FIG. 11B is a top view of the rotary hammer of FIG. 1 illustrating a chisel lock-on mechanism in a second position.

FIG. 12 is a side view of the rotary hammer of FIG. 1 illustrating a chisel lock-on mechanism according to another embodiment of the invention.

FIG. 13 is a perspective view of a chisel lock-on mechanism for use with the rotary hammer of FIG. 1 according to another embodiment of the invention.

FIG. 14 is a top view of the chisel lock-on mechanism of FIG. 13 .

FIG. 15 is a side view of the chisel lock-on mechanism of FIG. 13 .

Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways.

DETAILED DESCRIPTION

FIG. 1 illustrates a reciprocating percussive power tool, such as a rotary hammer 10, according to an embodiment of the invention. The rotary hammer 10 includes a housing 14, a motor 18 disposed within the housing 14, and a rotatable spindle 22 coupled to the motor 18 for receiving torque from the motor 18. In the illustrated construction, the rotary hammer 10 includes a quick-release mechanism 24 coupled for co-rotation with the spindle 22 to facilitate quick removal and replacement of a tool bit 25. The tool bit 25 includes a groove 25 a in which a detent member 26 of the quick-release mechanism 24 is received to constrain axial movement of the tool bit 25 to the length of the groove 25 a. The rotary hammer 10 defines a tool bit axis 27, which in the illustrated embodiment is coaxial with a rotational axis 28 of the spindle 22.

In the illustrated embodiment, the motor 18 is configured as a DC motor that receives power from an on-board power source 29 (e.g., a battery). The battery may include any of a number of different nominal voltages (e.g., 12V, 18V, etc.), and may be configured having any of a number of different chemistries (e.g., lithium-ion, nickel-cadmium, etc.). In some embodiments, the battery is a battery pack removably coupled to the housing 14. In other embodiments, the motor 18 may be powered by a remote power source (e.g., a household electrical outlet) through a power cord (not shown). The motor 18 is selectively activated by depressing an actuating member, such as a trigger 30, which in turn actuates an electrical switch 33. The switch 33 is electrically connected to the motor 18 via a top-level or master controller 31 (shown schematically in FIG. 1 ), or one or more circuits, for controlling operation of the motor 18.

The rotary hammer 10 further includes an impact mechanism 32 having a reciprocating piston 34 disposed within the spindle 22, a striker 38 that is selectively reciprocable within the spindle 22 in response to reciprocation of the piston 34, and an anvil 42 that is impacted by the striker 38 when the striker 38 reciprocates toward the tool bit 25. Torque from the motor 18 is transferred to the spindle 22 by a transmission 46. In the illustrated construction of the rotary hammer 10, the transmission 46 includes an input gear 50 engaged with a pinion 54 on an output shaft 58 of the motor 18, an intermediate pinion 62 coupled for co-rotation with the input gear 50 and an output gear 66 coupled for co-rotation with the spindle 22 and engaged with the intermediate pinion 62. The output gear 66 is secured to the spindle 22 using a spline-fit or a key and keyway arrangement, for example, that facilitates axial movement of the spindle 22 relative to the output gear 66 yet prevents relative rotation between the spindle 22 and the output gear 66. A clutch mechanism 70 is incorporated with the input gear 50 to limit the amount of torque that may be transferred from the motor 18 to the spindle 22.

With continued reference to FIG. 1 , the impact mechanism 32 is driven by a crank gear 78 that is rotatably supported within the housing 14 on a stationary shaft 82, which defines a central axis 86 that is offset from a rotational axis 90 of the output shaft 58 and pinion 54. As shown in FIG. 1 , the respective axes 86, 90 of the stationary shaft 82 and output shaft 58 are parallel. Likewise, respective axes 90, 98 of the output shaft 58 and the intermediate pinion 62 are also parallel. The impact mechanism 32 also includes a crank shaft 102 rotatably supported on the stationary shaft 82 and having an eccentric pin 110. The impact mechanism 32 further includes a connecting rod 116 interconnecting the piston 34 and the eccentric pin 110.

As shown in FIG. 2 , the rotary hammer 10 includes a mode selection dial 130 rotatable by an operator to switch between three modes. In a “rotary hammer” mode (position 1), the motor 18 is drivably coupled to the piston 34 for reciprocating the piston 34 while the spindle 22 rotates. In a “chisel” mode (positions 2 and 4), the motor 18 is drivingly coupled to the piston 34 for reciprocation while the spindle 22 is not rotated by the motor 18 but is free-floatingly allowed to rotate. In a “hammer-only” mode (position 3), the motor 18 is drivably coupled to the piston 34 for reciprocating the piston 34 but the spindle 22 is locked from rotation.

In operation, an operator selects rotary hammer mode with the mode selection dial 130. The operator then presses the tool bit 25 against the workpiece and depresses the trigger 30 to activate the motor 18. Rotation of the pinion 54 of the output shaft 58 causes the input gear 50 to rotate. Rotation of the input gear 50 causes the intermediate pinion 62 to rotate, which drives the output gear 66 on the spindle 22, causing the spindle 22 and the tool bit 25 to rotate.

Rotation of the pinion 54 also causes the crank gear 78 to rotate about the stationary shaft 82. Thus, the crank shaft 102 receives torque from the crank gear 78, causing the crank shaft 102 and the eccentric pin 110 to rotate about the central axis 86. Rotation of the eccentric pin 110 causes the piston 34 to reciprocate within the spindle 22 via the connecting rod 116, which causes the striker 38 to impart axial blows to the anvil 42, which in turn causes reciprocation of the tool bit 25 against a workpiece. Specifically, a variable pressure air pocket (or an air spring) is developed between the piston 34 and the striker 38 when the piston 34 reciprocates within the spindle 22, whereby expansion and contraction of the air pocket induces reciprocation of the striker 38. The impact between the striker 38 and the anvil 42 is then transferred to the tool bit 25, causing it to reciprocate for performing work on the workpiece.

While operating in rotary hammer mode, hammer only mode, or chisel mode the trigger 30 may operate manually by depressing and releasing the trigger 30 to activate the switch 33 and thus the motor 18. However, in hammer-only mode, the trigger 30 may be locked in a depressed position to continuously run the rotary hammer 10. In some embodiments, the trigger 30 may be biased away from the depressed position. As shown in FIGS. 3-5 , a chisel lock-on mechanism 134 may be used to manually lock the trigger 30 in the depressed position in which the switch 33 is activated and the motor 18 is continuously energized.

With reference to FIG. 3 , the chisel lock-on mechanism 134 includes a linkage 138, a shuttle 142, and a resilient member 146 (e.g., a leaf spring) (FIG. 4 ). The linkage 138 is supported on a top side of a gear housing 150 and includes a central opening 154 that receives a cam 158 of the mode selection dial 130. As the mode selection dial 130 is rotated, the cam 158 engages the inside surface of the central opening 154 to move the linkage 138 linearly in a direction perpendicular to the tool bit axis 27. The shuttle 142 is supported on a top portion of the housing 14 and extends from the housing 14 so as to be accessible by a user. A user may move the shuttle 142 in a direction parallel to the tool bit axis 27 between a manual position (FIG. 4 ) and a lock-on position (FIG. 5 ). In the illustrated embodiment, the shuttle 142 moves between the manual position and the lock-on position in a direction linearly rightward, as viewed from FIG. 5 . As the shuttle 142 is moved from the manual position to the lock-on position, a projection 162 on the shuttle 142 engages the resilient member 146 to deform the resilient member 146 so that a portion of the resilient member 146 extends into a recess 166 in the trigger 30 to lock the trigger 30 in the depressed position.

When the mode selection dial 130 is in either rotary hammer mode or chisel mode, an interference part 170 of the linkage 138 is in the travel path of the shuttle 142. As such, the shuttle 142 is prevented from moving to the lock-on position. When the mode selection dial 130 is in hammer only mode, the linkage 138 is at its lowest position (as viewed from FIG. 3 ) removing the interference part 170 of the linkage 138 from the travel path of the shuttle 142. As such, the shuttle 142 may be moved from the manual position to the locked-on position, which deforms the resilient member 146 into the recess 166 of the trigger 30 to lock the trigger 30 in the depressed state. With the trigger 30 locked in the depressed state, a user may remove their finger from the trigger 30 and the motor 18 will remain energized. Although not shown, biasing members, such as springs, may bias the linkage 138 away from the lowest position so that the interference part 170 of the linkage 138 is normally in the travel path of the shuttle 142.

FIG. 6 illustrates a chisel lock-on mechanism 210 according to another embodiment of the invention. The chisel lock-on mechanism 210 is similar to the chisel lock-on mechanism 134 discussed above with like features being represented with like reference numbers. The chisel lock-on mechanism 210 includes a shuttle 214 that is moveable between the manual position and the locked-on position. However, in contrast to the shuttle 142 discussed above, the shuttle 214 moves leftwards, as viewed from FIG. 6 , between the manual position and the locked-on position. The chisel lock-on mechanism 210 also includes a trigger 218 and a pawl 222. The trigger 218 is similar to the trigger 30 discussed above but includes ratchet teeth 226 adjacent the pawl 222. The pawl 222 is pivotably supported within the housing 14. Although not shown, a biasing member (e.g., a torsion spring) may bias the pawl 222 into engagement with the ratchet teeth 226. As such, when the shuttle 214 is in the manual position, a projection 230 engages the pawl 222 to move the pawl 222 out of engagement with the ratchet teeth 226 so that the trigger 218 can be manually depressed in and out of the depressed position.

When the rotary hammer 10 is operating in hammer only mode, the shuttle 214 is allowed to move from the manual position to the lock-on position. As the shuttle 214 moves from the manual position to the lock-on position, the pawl 222 is biased into engagement with the ratchet teeth 226. Now, if a user depresses the trigger 218, the pawl 222 will slide over the ratchet teeth 226 until the trigger 218 is in the depressed position. The pawl 222 will then engage one of the ratchet teeth 226 to lock the trigger 218 in the depressed position which activates the switch 33 and continuously runs the motor 18 allowing a user to remove their finger form the trigger 218 and still operate the rotary hammer 10. To release the trigger 218 from the depressed position, the user may move the shuttle 214 from the lock-on position to the manual position. The projection 230 on the shuttle 214 will engage the pawl 222 to move the pawl 222 against the bias of the trigger 218 allowing the trigger 218 to move from the depressed position.

FIG. 7 illustrates a chisel lock-on mechanism 310 according to another embodiment of the invention. The chisel lock-on mechanism 310 is similar to the chisel lock-on mechanism 210 discussed above with like features being represented with like reference numbers. The chisel lock-on mechanism 310 includes a shuttle 314 that is moveable between the manual position and the locked-on position in a direction rightwards, as viewed from FIG. 7 . The chisel lock-on mechanism 310 also includes a trigger 318 and a pivot bar 322. The trigger 318 is similar to the trigger 218 discussed above and includes ratchet teeth 326 adjacent the pivot bar 322. The pivot bar 322 includes a first end 330 that pivotably couples the pivot bar 322 to the housing 14 and a second end 334 opposite the first end 330. The second end 334 of the pivot bar 322 includes a hook portion 338 and a ramp portion 342. The ramp portion 342 is supported within an opening 346 of a projection 350 of the shuttle 314. A biasing member 354 (e.g., a compression spring) biases the pivot bar 322 in a clockwise direction.

When the rotary hammer 10 is operating in the hammer only mode, the shuttle 314 is allowed to move between the manual position and the lock-on position. As the shuttle 314 moves from the manual position to the lock-on position, the projection 350 slides along the ramp portion 342 of the pivot bar 322 allowing the hook portion 338 of the pivot bar 322 to rotate about an axis that is perpendicular to the tool bit axis 27 towards the ratchet teeth 326 of the trigger 318 due to the bias of the compression spring 354. Once the hook portion 338 engages the ratchet teeth 326, the trigger 318 is locked in the depressed position which activates the switch 33 and continuously runs the motor 18. To release the trigger 318 from the depressed position, a user may move the shuttle 314 from the lock-on position to the manual position. As the shuttle 314 moves from the lock-on position to the manual position, the projection 350 slides along the hook portion 338 of the pivot bar 322 to pivot the hook portion 338 out of engagement with the ratchet teeth 326 allowing the trigger 318 to move from the depressed position.

FIG. 8 illustrates a chisel lock-on mechanism 410 according to another embodiment of the invention. The chisel lock-on mechanism 410 is similar to the chisel lock-on mechanism 310 discussed above with like features being represented with like reference numerals. The chisel lock-on mechanism 410 includes a shuttle 414, a trigger 418 but further includes a plunger mechanism 422. The plunger mechanism 422 is supported within the housing 14 of the rotary hammer 10. The plunger mechanism 422 includes a plunger housing 426 and a plunger 430. The plunger housing 426 includes a ramp surface 434 that engages a ramp surface 438 on the shuttle 414. A first outer spring 442 biases the plunger housing 426 in a direction away from the trigger 418 (i.e., upwards as viewed from FIG. 8 ). A second inner spring 446 biases the plunger 430 in a direction towards the trigger 418 (i.e., downwards as viewed from FIG. 8 ).

When the rotary hammer 10 is operating in hammer only mode, the shuttle 414 is allowed to move between the manual position and the locked-on position. When the shuttle 414 is in the manual position, there is enough clearance between the plunger 430 and the plunger housing 426 that the trigger 418 slides over the plunger 430 when moving in and out of the depressed position. Alternatively, when the shuttle 414 is in the locked-on position, the ramp surface 438 of the shuttle 414 engages the ramp surface 434 of the plunger housing 426 to move the plunger housing 426 against the bias of the first spring 442. With the ramp surfaces 434, 438 engaged, the plunger 430 is positioned closer to the trigger 418. As the trigger 418 is moved in to the depressed position, the plunger 430 is biased into a recess 450 of the trigger 418 to lock the trigger 418 in the depressed state and activate the switch 33 to continuously energize the motor 18. To release the trigger 418 from the depressed state, a user may move the shuttle 414 from the locked-on position to the manual position, which disengages the ramp surfaces 434, 438 allowing the plunger housing 426 to move back to its original position and removing the plunger 430 form the recess 450.

FIG. 9A illustrates a chisel lock-on mechanism 510 according to another embodiment of the invention. The chisel lock-on mechanism 510 is similar to the chisel lock-on mechanism 310 discussed above with like features being represented with like reference numbers. The chisel lock-on mechanism 510 includes the mode selection dial 130, a linkage 514 with an interference part 518, a shuttle 522, a pivot bar 526, a trigger 530, and a microswitch 534 that is in communication with the controller 31. In the illustrated embodiment, when the shuttle 522 is in the manual position (FIG. 9A), the trigger 530 is a variable speed trigger. In other words, the amount the trigger 530 is depressed correlates to the speed the motor 18 rotates the tool bit 25. However, when the microswitch 534 is activated, if the trigger 530 is depressed, the controller 31 disables the variable speed capability of the trigger 530 and runs the motor 18 at full speed. As such, when the shuttle 522 is moved to the locked-on position (FIG. 9B), a flexible member 538 (i.e., a leaf spring) on the shuttle 522 engages and activates the microswitch 534. Meanwhile, the pivot bar 526 engages a recess 542 on the trigger 530 to lock the trigger 530 in the depressed state and activate the switch 33 and continuously run the motor 18 at full speed. Once the shuttle 522 is moved back to the manual position, the microswitch 534 is deactivated, allowing the user to again vary the speed that the motor 18 rotates the tool bit 25.

With reference to FIGS. 10A-11B, the mode selection dial 130 is rotatable to the plurality of positions (1-4) discussed above. The mode selection dial 130 includes an indicator 550 that points to indicia on the top of the housing 14 corresponding to the plurality of positions. With reference to FIGS. 10A and 10B, the mode selection dial 130 and the chisel lock-on mechanism 510 are in a first position corresponding to a rotary hammer mode. When the mode selection dial 130 is in rotary hammer mode, the cam 158 positions the linkage 514 at its highest position (as viewed from FIG. 10B). When the linkage 514 is at its highest point the interference part 518 is in the travel path of the shuttle 522. As such, the shuttle 522 is prevented from moving to the lock-on position and the flexible member 538 is incapable of engaging and activating the microswitch 534. Therefore, when the trigger 530 is depressed, the controller 31 allows the user can vary the speed that the motor 18 rotates the tool bit 25.

With reference to FIGS. 11A and 11B, the mode selection dial 130 and the chisel lock-on mechanism 510 are in a second position corresponding to a hammer-only mode. When the mode selection dial 130 is in hammer only mode, the cam 158 positions the linkage 514 at its lowest position (as viewed from FIG. 11B) removing the interference part 518 of the linkage 514 from the travel path of the shuttle 522. As such, the shuttle 522 may be moved from the manual position to the locked-on position, which allows the flexible member 538 to engage and activate the microswitch 534. Therefore, when the trigger 530 is depressed, the controller 31 disables the variable speed capability of the trigger 530 and runs the motor 18 at full speed. Meanwhile, the pivot bar 526 engages the recess 542 on the trigger 530 to lock the trigger 530 in the depressed state and activate the switch 33 and continuously run the motor 18 at full speed. Once the shuttle 522 is moved back to the manual position, the microswitch 534 is deactivated allowing the user to vary the speed the motor 18 rotates the tool bit 25.

FIG. 12 illustrates a chisel lock-on mechanism 610 according to another embodiment of the invention. The chisel lock-on mechanism 610 is similar to the chisel lock-on mechanism 510 discussed above with like features being represented with like reference numerals. However, instead of the pivot bar 526, the chisel lock-on mechanism 610 includes a lock latch 614 pivotably supported within the housing 14. The lock latch 614 includes a first arm 618 and a second arm 622 opposite the first arm 618. A biasing member 626 (e.g., a torsion spring) biases the lock latch 614 in a counterclockwise direction so that the first arm 618 engages a projection 630 on the shuttle 522.

When the rotary hammer 10 is in hammer only mode the shuttle 522 is moveable between the manual and lock-on positions. As the shuttle 522 moves from the manual position to the lock-on position, the projection 630 pivots the lock latch 614 against the bias (e.g., clockwise) of the biasing member 626. As the lock latch 614 pivots, the second arm 622 of the lock latch 614 extends into a recess 634 of the trigger 530 to lock the trigger 530 in the depressed position and activate the switch 33 to continuously energize the motor 18. To release the trigger 530 from the depressed state, a user may move the shuttle 522 from the locked-on position to the manual position, which allows the biasing member 626 to pivot the lock latch 614 counterclockwise. As the lock latch 614 pivots, the second arm 622 is removed from the recess 634 and the trigger 530 is allowed to move from the depressed position.

FIGS. 13-15 illustrate a chisel lock-on mechanism 710 according to another embodiment of the invention. The chisel lock-on mechanism 710 includes a linkage 714, a cam lock 718, a shuttle 722, a lock latch 726, and a trigger 728 (FIG. 15 ). The linkage 714 is positioned on a top side of a gear box 730 and includes an opening 734 that the cam 158 of the mode selection dial 130 extends into. The cam lock 718 is pivotably coupled to a stem 738 of the linkage 714 for movement between a first position, in which the cam lock 718 prevents movement of the shuttle 722, and a second position, in which the cam lock 718 is removed from the travel path of the shuttle 722. The shuttle 722 is moveable between a manual position and a lock-on position when the cam lock 718 is in the second position.

During operation, when the mode selection dial 130 is rotated to the hammer only mode (i.e., position 3), the linkage 714 is moved to its lowest point (as viewed in FIG. 14 ), which in turn pivots the cam lock 718 to the second position and out of the travel path of the shuttle 722. The shuttle 722 can then be moved from the manual position to the lock-on position. Similar to the lock latch 614 discussed above, as the shuttle 722 moves from the manual position to the lock-on position, a projection 742 pivots the lock latch 726 against the bias (e.g., clockwise) of a biasing member (not shown) allowing the second arm 746 of the lock latch 726 to extend into a recess 750 of a trigger 728 to lock the trigger 728 in the depressed position and activate the switch 33 to continuously energize the motor 18. To release the trigger 728 from the depressed state, a user may move the shuttle 722 from the locked-on position to the manual position, which allows the biasing member to pivot the lock latch 726 counterclockwise. As the lock latch 726 pivots, the second arm 746 is removed from the recess 750 and the trigger 728 is allowed to move from the depressed position.

Although the invention has been described in detail with reference to certain preferred embodiments, variations and modifications exist within the scope and spirit of one or more independent aspects of the invention as described.

Various features of the invention are set forth in the following claims. 

What is claimed is:
 1. A rotary hammer operable in a first mode in which only a hammering operation to reciprocate a tool bit along a drive axis is performed and a second mode in which the tool bit is rotationally driven about the drive axis, the rotary hammer comprising: a motor; a controller to control operation of the motor; a trigger moveable between an off position, in which the motor is not energized, and an on position, in which the motor is energized; a mode selection dial operable to select the first or second mode; a lock mechanism moveable between a first position, in which, the trigger is moveable between the on and off positions, and a second position, in which the trigger is maintained in the on position; a linkage moveable between a third position, in which, when the mode selection dial selects the first mode, the lock mechanism is able to move between the first and second positions, and a fourth position, in which, when the mode selection dial selects the second mode, the lock mechanism is inhibited from moving between the first and second positions; and a switch in communication with the controller, wherein the switch, in a first state, communicates with the controller to operate the motor at full power, and the switch, in a second state, communicates with the controller to operate the motor at a variable speed based on the position of the trigger between the on position and the off position.
 2. The rotary hammer of claim 1, wherein the switch is in the first state when the lock mechanism is in the second position.
 3. The rotary hammer of claim 2, wherein the lock mechanism engages the switch in the second position to toggle the switch from the second state to the first state.
 4. The rotary hammer of claim 1, further comprising: a spindle; and a reciprocating impact mechanism operable to create a variable pressure air spring within the spindle, the impact mechanism including a striker received within the spindle for reciprocation along the drive axis in response to a pressure of the variable pressure air spring, the striker imparting axial impacts to the tool bit.
 5. The rotary hammer of claim 4, wherein the reciprocating impact mechanism further includes piston that reciprocates within the spindle to induce the variable pressure air spring and a crank shaft configured to convert continuous rotational motion from the motor to reciprocating linear movement of the piston.
 6. The rotary hammer of claim 1, wherein the linkage includes an interference part that inhibits the lock mechanism from moving between the first and second positions when the linkage is in the fourth position.
 7. The rotary hammer of claim 1, wherein the mode selection dial moves the linkage between the third and fourth positions.
 8. The rotary hammer of claim 7, wherein the mode selection dial includes a cam that engages the linkage to move the linkage between the third and fourth positions.
 9. The rotary hammer of claim 1, wherein the lock mechanism further includes a pivot bar pivotable to engage the trigger to maintain the trigger in the on position.
 10. A rotary hammer operable in a first mode in which only a hammering operation to reciprocate a tool bit along a drive axis is performed and a second mode in which the tool bit is rotationally driven about the drive axis, the rotary hammer comprising: a motor; a controller to control operation of the motor; a trigger moveable between an off position, in which the motor is not energized, and an on position, in which the motor is energized; a mode selection dial operable to select the first or second mode; a lock mechanism including a shuttle moveable linearly between a first position, in which, the trigger is moveable between the on and off positions, and a second position, in which the trigger is maintained in the on position; a linkage moveable between a third position, in which, when the mode selection dial selects the first mode, the shuttle is able to move from the first position to the second position, and a fourth position, in which, when the mode selection dial selects the second mode, the shuttle is inhibited from moving from the first position to the second position; and a switch in communication with the controller, wherein the switch, in a first state, communicates with the controller to operate the motor at full power, and the switch, in a second state, communicates with the controller to operate the motor at a variable speed based on the position of the trigger between the on position and the off position.
 11. The rotary hammer of claim 10, wherein the shuttle moves in a direction parallel to the drive axis between the first and second positions.
 12. The rotary hammer of claim 10, further comprising a housing, wherein the shuttle is supported on a top portion of the housing.
 13. The rotary hammer of claim 10, wherein the lock mechanism further includes a pivot bar, wherein as the shuttle is moved from the first position to the second position the pivot bar pivots to engage the trigger to maintain the trigger in the on position.
 14. The rotary hammer of claim 13, wherein the pivot bar is pivotable about an axis that is perpendicular to the drive axis.
 15. The rotary hammer of claim 13, wherein the pivot bar is biased to engage the trigger.
 16. The rotary hammer of claim 13, wherein the trigger includes a recess, and wherein the pivot bar engages the recess to maintain the trigger in the on position.
 17. The rotary hammer of claim 10, further comprising a housing and a battery pack that is removably coupled to the housing to energize the motor.
 18. The rotary hammer of claim 10, wherein the mode selection dial is rotatable to select between the first and second modes.
 19. The rotary hammer of claim 10, wherein the linkage moves linearly between the third and fourth positions.
 20. The rotary hammer of claim 19, wherein the linkage moves in a direction perpendicular to the drive axis between the third and fourth positions.
 21. A rotary hammer operable in a first mode in which only a hammering operation to reciprocate a tool bit along a drive axis is performed and a second mode in which the tool bit is rotationally driven about the drive axis, the rotary hammer comprising: a motor; a trigger moveable between an off position, in which the motor is not energized, and an on position, in which the motor is energized; a mode selection dial operable to select the first or second mode; a lock mechanism including a shuttle moveable in a direction parallel to the drive axis between a first position, in which the trigger is moveable between the on and off positions, and a second position, in which the trigger is maintained in the on position; and a linkage moveable between a third position, in which, when the mode selection dial selects the first mode, the shuttle is able to move from the first position to the second position, and a fourth position, in which, when the mode selection dial selects the second mode, the shuttle is inhibited from moving from the first position to the second position.
 22. The rotary hammer of claim 21, wherein the linkage is movable between the third and fourth positions in a direction perpendicular to the drive axis.
 23. The rotary hammer of claim 21, wherein the lock mechanism further includes a resilient member engageable with the trigger to maintain the trigger in the on position when the shuttle is in the second position.
 24. The rotary hammer of claim 21, wherein the lock mechanism further includes a pawl engageable with ratchet teeth of the trigger to maintain the trigger in the on position when the shuttle is in the second position.
 25. The rotary hammer of claim 21, wherein the lock mechanism further includes a pivot bar pivotable to engage the trigger to maintain the trigger in the on position when the shuttle is in the second position.
 26. The rotary hammer of claim 21, wherein the lock mechanism further includes a plunger mechanism biased to engage the trigger to maintain the trigger in the on position when the shuttle is in the second position.
 27. The rotary hammer of claim 26, wherein the plunger mechanism includes a plunger that is biased to engage the trigger when the shuttle is in the second position.
 28. The rotary hammer of claim 21, wherein the lock mechanism further includes a lock latch that is rotatable to engage the trigger to maintain the trigger in the on position when the shuttle is in the second position.
 29. The rotary hammer of claim 21, further comprising a housing, wherein the shuttle is supported on a top portion of the housing.
 30. The rotary hammer of claim 21, further comprising: a controller to control operation of the motor; and a switch in communication with the controller, wherein the switch, in a first state, communicates with the controller to operate the motor at full power, and the switch, in a second state, communicates with the controller to operate the motor at a variable speed based on the position of the trigger between the on position and the off position.
 31. The rotary hammer of claim 30, wherein the shuttle engages the switch in the second position to toggle the switch from the second state to the first state. 